Embodiments of the present invention relate generally to methods for machining substrates of glass and, more specifically, to methods for machining features (e.g., through-holes, apertures, openings, etc.) in strengthened glass substrates. Embodiments of the present invention also relate to apparatuses for machining substrates of glass, and to articles of strengthened glass.
Thin strengthened glass substrates, such as chemically- or thermally-strengthened substrates have found wide-spread application in consumer electronics because of their excellent strength and damage resistance. For example, such glass substrates may be used as cover substrates for LCD and LED displays and touch applications incorporated in mobile telephones, display devices such as televisions and computer monitors, and various other electronic devices. To reduce manufacturing costs, it may be desirable that such glass substrates used in consumer electronics devices be formed by performing thin film patterning for multiple devices on a single large glass substrate, then sectioning or separating the large glass substrate into a plurality of smaller glass substrates using various cutting techniques.
However the magnitude of compressive stress and the elastic energy stored within the central tension region may make machining of chemically- or thermally-strengthened glass substrates difficult. The high surface compression and deep compression layers make it difficult to mechanically machine the glass substrate (e.g., by sawing, drilling, etc.) using conventional techniques. Furthermore, if the stored elastic energy in the central tension region is sufficiently high, the glass may chip or shatter when the surface compression layer is penetrated. In other instances, the release of the elastic energy may generate cracks within the substrate, which can ultimately reduce the strength of the machined article. Accordingly, a need exists for alternative methods for machining features in strengthened glass substrates.